Machine for grinding worn-threads.



C. H. CALKINS.

MACHINE FOR GRINDING woam THREADS.-

APPLICATION FILED MAR. 17, I916.

3 SHEETSSHEET l- 1,27-5,g1 .PatentedAug. 13,1918.

v INVENTORI 1 I WITNESS E? v WWW C. H. CALKINS. MACHINE ron GRINDING WORM THREADS.

APPLICATION FILED MAR. 17. I916.

Patented. Aug. 13, 1918.

3 SHEETS-SHEET 2- By Attorney WITNESS C. H. CALKINS.

MACHINE FOR GRINDING WORM THREADS. APPLICATION FILED MAR. 17. I9I6.

' Patented Aug. 13, 1918 3 SHEETSSHEET 3- //m22;i;ii;

I By Attorney,

WITNESS enemas r1. carxf'rns, or runtowgnns sncnusnrrs, Assrenon 'ro BAUSH MACHINE roor. comrm, a ccnronn'rlon' or nnssncnusnrrs.

MACHINE FOIL GRINDING- WORM-THREADS.

Specification of Letters Patent.

Patented Aug. 13, 1918,

Application filed. March 17, 1916. Serial No. 84,854.

To all whom/it may concern:

Be it known that L'CHARLES H. OALKINS, a citizen of the United States, residing in Ludlow, Massachusetts, have :invented certain new and useful Improvements. in lMa chines for Grinding .Worm-Threads," of which the following is a specification;

The invention aims to provide a machinev for grinding worm, threads with an emery or other abrading wheel. The worms-rof wormgearingare ordinarilyvmade of steel and after being cut to shape are hardened by heat treatment which sometimes distorts the shape of the thread and lessensits efliciency. Such threads, therefore, are ground down to. the exact shapedsired by meansof abrading wheels. The invention provides a machine of greatsimplicit and accuracy for performing such a grin 'ng' operationyautomatically. k The accompanying drawings illustrate an embodiment.qflthemventiont -u l I Figure 1-1s aside elevation of a worm such as the illustrated machine is adapted to v. I' g l! Fig.'2--1s a cross-sectlonof thesame on. the, line 22, Fig. 1, showing the grinding wheel also in place Fig. 3 is a side elevation of the machine with a detail thereof in section;

Figs. stand 5 are respectively a plan and an end elevation-ofi the machine. a A

1 Theworm is formed with end portions A. and -B of vari'ous shapes forwarious uses and grithdasncintermeglilaizerthreaided rgfortioni, t at v ea i w i f ig. -2, ."are orme with inclined l eari iig faces {1). "The grindg operation isperformedon these, inclined faces I) .of the spiralxthreads. The machineis provided with a beveled abrading'wheel .E, the beveled faces F of which bear a ainst the beveled ,faces D of the worm an the worm is fed spirally so that its beveled faces are ground to a true spiral as the wheel rotates against them. The feed mechanismgis driven" from a belt pulle'y. G-,Fig. 4, one. shaft H, Fig. 3, which through beveled gearing -J. drives a longi-- tudinal shaft K on the end of which is'a worm, L driving a wormgear PM onlxthe shaft N which carries a pinion, N engag-.

othen spiral worms; the stud on ways U. On the bed Tis carried a tail stock V with a pin W engagin the'end B of the worm to be ground an permitting rotation of the same. The bed 'I carries also a head stock X in which is rotatably mounted a shaft Y which is fastened fixedly on the end Act the worm. A master worm Z is rnrnnr enrich;

fixedly fastened onthe shaft Y of the head stock and is carried at its outer ends in bearings on the supplementary head a. The thread I; of the master worm is of exactly the same lead as the threads 0 of the worm which isto be ground. The thread of the 7 master worm is engaged by a stud c with a tooth-shaped end, the stud being carried fixedly-in a heavy bracket Z which is fastened solidly-"to the frame e of the machine. A nutfis fixed on the top of the bracket d and thestud 0 can be screwed into or out of the same by means of a pin 9 fastened. inthe top otthestud, The master wormlZ may be withdrawn and another worm of different pitch substituted therefor so as to grind v 0 being adjustable. as explained for difi'erent master worms. Now when the'bed T is moved forward by the gearing described it carries with it the tail stock V, the worm C, head stock X and supplementary head stock a, and with them the master worm Z. The bracket d and stud c beingfixed, cause the master worm Z, to rotate as it is advanced, andwiththe master worm rotates the \worm' C which is to be ground, thus insuring that the abrading when Eshall run exactly in the proper lead In previous. machines for grinding-the faces of WOI'III threads the longitudinal movement has been obtained, by a various means-and the rotary movement has been obtained by a series of gears! driven from the'gears which effect the longitudinal movement, soias .to secure the desired ratio be tween the longitudinal speed and vthe rotary speed of the work; and change gears have been used forfchanging the ratio. ii; Such ma chines involve a considerable amount of gearing to secure the desired-ratio and adjustability of ratio and these. gears; besides being complicated, have necessarily involved a certain lost motion whichmade it diifi,

cult to secureperfectaccuracy. An advantage of the present machine lies in the mounting of the means foriotating the work directly and fixedly on the. work, so

that it is the exact advance of the work itself which determines the rate of rotation and the latter is, therefore, exactly coiirdinated with the rate of advance in the axial direction. At the same time the mechanism for securing rotation at the proper rate of speed is the simplest possible, andehange of ratio can be effected with the greatest ease.

The abrading wheel E is mounted on a spindle h which is rotated at a rapid rate by a pulley j driven'by a sprocket chain is from a motor Z overhead. The drivin of the :ibrading wheel, therefore, is entirely separate and distinct from the driving of the other movable elements of the machine. The motor unit, including the abrading wheel, is mounted on a turn table consisting of plates m, n embracing a cross head 0 and having a circular portion ;0 rotating within a circular opening in the cross head. The central axis of rotation is indicated at g in Fig. 2. It passes through the center of the abrading wheel E. The latter can, therefore, be

. turned about this vertical axis so as to fit its beveled edge between worm threads of any angle. The abrading wheel can be easily withdrawn from the end of its spindle and replaced by another with a different, bevel to fit it between worm threads having their far-es beveled at difl'erent angles.

'ihe' abrading wheel with its motor can also be adjusted vertically to fit it for grinding worms of different diameters and to permit it to be fed progressively deeper into the work and to be withdrawn from between a pair of finished threads and introduced into engagement with the beveled faces of a new pair of threads. For. thispurpose the entire cross head 0 is provided with slides r engaging guides 8 carried fixedly by the frame of the machine, and the slides 1' are threaded on the upper ends of shafts t which at their lower ends carry beveled gears M (Fig. 5) engaging pinions 'v on a transversely extending shaft w which has at one end a gear 00 driven from a gear y on a shaft 2 which is driven from a beveled gear 1 at its upper end engaging a similar gear 2 on a shaft 3 on the outer end of which is fixed a hand wheel 4. The hand wheel is graduated as indicated in Fig. 5 on its edge and rotates in juxtaposition to a, fixed disk 5 carrying an index line, the graduations being proportioned to a. movement of a thousandth of an inch of vertical movement of the abrading wheel. When a grinding operation begins the wheel is brought down to engage the beveled side faces of the threads. As the grinding progresses the wheel is fed downward step by step until it makes a full engagement with the beveled faces of the worm thread and grinds it truly throughout the depth of such faces.

The abrading wheel E, asshown in Fig.

5, is arranged so that its diameter throughmsm acts directly on rename ment the feeding of the grinding wheel is in the direction of the radius of the work, and

a simple rectilinear adjustment is all that is necessary to feed it farther into the work for successive grinding operations.

It has been proposed heretofore to use a lead screw, of the same itch as the work, in machines of this genera class, that is where a spiral movement of the work is to be secured; the drivin mechanism impressing a rotary movement directly, and the lead screw converting this into a spiral. With such apparatus however, change gears cannot be avoided if the machine is to take a considerable variety of work. It is necessary in some cases to rotate the work more rapidly and in other cases to rotate it more slowly for corresponding linear movement. With my improved machine, the driving'mechathe reciprocating bed, and the'master worm imposes on the work exactly the rotary speed desired.

In Fig. 2 the worm is indicated as having six threads, and the grinding wheel engaging two threads at the same, time. vWorms are made with from one to six or even more threads and generally in grinding the wheel will engage only one thread at a time, two operations being required for the of the two faces of each thread. After'one thread has been ground the worm must be rotated with respect to the master worm Z. In the case of a worm havin sixthreads,

this must be niven one-sixth c a turn in ad-. vance of the master worm, before the emery wheel is again moved down into engagement. This adjustment will be repeated six times for the worm having six threads. The adjustment'is accomplished by means of a serrated indexing disk Y (Fig. 3)"which coiiperates with any usual or suitable latch.

and permits the worm to be advanced any desired fraction ahead of the master worm. After the adjustment is efiected, the worm to be ground and the master worm remain fixed to each other until the worm is com-' pleted. v atlclaimis- 1. A. machine for grinding the beveled side faces of worm threads including in combination means for advancing the work axially and a master worm for rotating it, a beveled abrading wheel adapted to be set at the angle of the threads to be ound,

with its beveled face engaging the eveled.

faces of such threads and its diameter through the point of enga ement lying 'at right angles to the axis 0 the work and not let

means for feeding such abrading whee farther into the work in a direction normal to the axis thereof as the grinding pro esses. 2. A machine for grinding the eveled faces of worm threads including in combiside faces of worm threads, including in,

combination a reciprocable bed T, a tail stock carried by said bed and adapted to engage one end of the worm to be ground and to permit rotation of the same, a head stock X also carried by said bed, a shaft Y mounted in said head stock and adapted to be fastened fixedly on the opposite end of the worm to be ground, a master worm fixedly fastened on the shaft Y, a fixed device engaging the thread of said master worm and causing the same to be rotated and advanced axially with the work at the same rate as the threads on the work, and an abrading wheel adapted to simultaneously engage the adjacent threads of the work.

4. A machine for grinding the beveled side faces of worm threads including in combination a reciprocable bed T, a tail stock carried by said bed and adapted to engage one end of the worm to be ground and to permit rotation of the same, a head stock X also carried by said bed, a shaft Y mounted in said head stock and adapted to be fastened fixedly on the opposite end of the worm to be ground, a master worm fixedly fastened on the shaft Y, a fixed device engaging the thread of said master worm and causing the same to be rotated and advanced axially with the work at the same rate as the threads on the work, and an abrading wheel adapted to simultaneously engage the adjacent faces of the threads of the work, the means for fastening the shaft Yto the work being adapted to eflect an angular El-(lJllStlTlQIlt between such parts.

5. A machine for grinding the beveled faces of worm threads including in combina *tion a bed and rotary means acting directly thereon to continuously reciprocate the same, a master worm rotatably mounted on said bed, a fixed device engaging the thread of the master worm, said master worm being rotated solely by the reciprocation of the bed and the cooperation of the said fixed device, and means forrigidly attaching'the work to the master worm.

6. A machine for. grinding the beveled side faces of worm threads including in combination means for advancing the work aXially'and a master worm for rotating it,

a beveled abrading wheel adapted to be set at the angle of the threads to be ground, with its beveled face engaging the beveled faces of suchthreads and its diameter through the point of engagement lying atright angles to the .axis of the work, a motor for driving -said abrading wheel, a rotatable base for supporting said motor and said abrading wheel.-

In witness whereof, I have hereunto signed my name.

CHARLES H. CAELKINS. 

